Systems exist that determine if objects are in a queue. For example, FIG. 6 illustrates a retail environment 50 that includes two service locations 52a, 52b (e.g., cash register locations, etc.). Two objects (e.g., tracked customers, images of retail customers, etc.) 54a, 54b are shown at the two respective service locations 52a, 52b. Two objects 56a, 56b are awaiting service at the first service locations 52a in a first queue 56, and another object 58a is awaiting service at the second service location 52b in a second queue 58. Another object 60 is passing between the two queues 56, 58, moving in the direction of the service locations, and does not intend to enter either of the queues 56, 58. Yet another object 62 is at a display 64, and does not intend to enter either queue.
Prior systems attempted to determine which objects are in a queue, such as the first queue 56 and the second queue 58, by tracking the positions of each object (e.g., by way of an image tracking device or other sensor) in a region of interest for each queuing location. For example, a first region of interest 66 might be established to determine which objects, if any, are waiting in the first queue 56 to be serviced by the first service location 52a. A second region of interest 68 might be established to determine which objects, if any, are awaiting service in the second queue 58 by the second service location 52b. In such prior systems, it is difficult to determine which objects are located within one of the queues, if objects can perform other tasks in or near the regions of interest 66, 68. For example, the object 60 that is passing between the two queues 56, 58 is within the first region of interest 66, and therefore might inaccurately be determined by prior systems to be in the first queue 56. Additionally, the object 62 examining the product display 64 is within the second region of interest 68, and therefore might inaccurately be determined by prior systems to be in the second queue 58. Moreover, such systems are unable to determine if the queues 56, 58 extend outside the respective regions of interest 66, 68, such as when the queue curves or bends. Thus, as can be seen from the above description, prior systems might inaccurately characterize some objects that are not within a queue (e.g., objects 60, 62) as being within a queue, and might omit some objects that are waiting in a queue from being characterized as being within the queue, depending upon the correlation of the geometry of the regions of interest 66, 68 with the shape of the queue.